Field of the Invention
One or more aspects of the present invention relate to a hi-fi audio device and a method of removing noise in a power supply.
Background Art
In general, an audio device is a system configured to record a sound wave that is in a range of sound that a human ear can hear (e.g., music, a human voice, natural sound, etc.) and an electrical signal converted from the sound wave, or to convert a recorded signal into the energy of a sound wave and emit the energy of the sound wave to the space.
A hi-fi audio device is an audio system capable of reproducing sound to be close to the original and uniformly from a low note to a high note within a human audible frequency range of 16 Hz to 20 kHz. The hi-fi audio device is very sensitive to noise, and particularly, to alternating current (AC) power-line noise occurring in an AC power supply used as an external power supply.
Electrical devices operating with an AC power supply are connected to a common power supply line. Thus, AC power-line noise occurring in one electrical device may cause another electrical device connected thereto via the common power supply line (ADD OK?) to malfunction, or the electrical device may be influenced by noise occurring in the other electrical device and thus malfunction. Thus, an AC power supply of an electronic device may act as an entrance or an exit through which noise penetrates into the electronic device. Furthermore, such noise may be a major factor that degrades the quality of sound reproduced by the hi-fi audio device.
The AC power-line noise may be classified as high frequency noise, pulse noise, or surge noise according to a voltage or waveform thereof.
The high frequency noise is a harmonic component contained mainly in a switching frequency of a computer, a switching power supply, etc., has a voltage of several of mV to several tens of mV, and always occurs when an electrical device is ‘on’ or ‘off’.
The pulse noise occurs during switching of a relay or induction motor, and has a voltage which is higher than that of the high frequency noise. A peak voltage of the pulse noise may reach several thousands of volts.
The surge noise occurs in a power supply line mainly by induction lightning and has a voltage which is far higher than those of the high frequency noise and the pulse noise. A peak voltage of the surge noise may reach several tens of thousands of volts.
An electrical device including an integrated circuit (IC) chip may be directly influenced by the pulse noise and the surge noise, and may act as a source of generating the high frequency noise. Thus, the electrical device including the IC chip affects other electrical devices or the electrical device itself.
To solve problems caused by noise in a power supply as described above, a method of using a noise filter, a method of separating a panel board, etc. have been introduced. However, these methods are limited in that the size of an electrical device should be increased and a noise preventing device, etc. should be additionally included, and in view of an economic aspect.
Furthermore, in an audio device according to the related art, one battery supplies power to perform various operations, e.g., to reproduce a sound source, perform a system operation, amplify a sound source, etc. However, the intensities of current needed for elements of the audio device to perform the various operations are different. Thus, when an appropriate intensity of current is not supplied to each of these elements of the audio device, system noise occurs in the audio device according to the related art.